When a self-styled King of the Rats crashes a corporate do hosted by Fleet and Tyburn naturally the Folly are called in. Peter and Kumar have to determine whether his majesty is the legitimate ruler of the rat nation or a sad man with a rodent fixation. And they’d better do it fast before irate Rivers decide to embark on a bit of DIY pest control. King of the Rats is short story written by Ben Aaronovitch. The story was written exclusively for Cityread London 2015. It was read publicly by Doc Brown (Ben Bailey Smith) at the Mail Rail. It was an 'extra' in the paperback Waterstones edition of The Hanging Tree.